package com.stu;

import java.util.HashSet;
import java.util.Set;

/**
 * Created by chenhs on 2019/1/17.
 */
public class Test {

    public static void main(String[] args) {

        Set<Long> set = new HashSet<>();

        Set<Long> copy = new HashSet<>(set);

        copy.add(100L);
        copy.add(100L);
        copy.add(101L);
        copy.add(101L);

        System.out.println(copy);

    }

}
